This invention is concerned with improvements in or relating to adhesive-applying apparatus whereby a layer of moisture-curable adhesive in a molten state can be applied to a surface portion of a workpiece presented to an operating locality of the apparatus.
There is described in U.S. Pat. No. No. 4,419,393 an adhesive-applying apparatus comprising a tapering block which constitutes a flexible blade member, said block terminating in a narrow spreading surface or spreading edge and one, adhesive-guiding, surface of the block being concave about an axis which extends transversely of the spreading edge, the arrangement being such that, when the adhesive-applying apparatus is in use, adhesive is supplied to the adhesive-guiding surface, which is arranged "upstream" (in terms of the direction of relative movement between the nozzle and a workpiece to which adhesive is being applied) of the spreading edge, whereby a pool of adhesive is formed within the confines of the concavity and the spreading edge acts to control the thickness of the adhesive layer applied to the workpiece.
In using such an apparatus, the workpiece is presented manually to the apparatus and thus, it will be appreciated, reliance must be placed upon the skill of the operator in controlling the pressure by which the workpiece is urged against the flexible blade member, which in turn controls the thickness of the applied layer of adhesive. Of course, as the operator becomes skilled, a consistent layer thickness becomes achievable, but initially achieving such consistency is difficult, especially in the case of presentation of an irregular non-flat workpiece, e.g. a shoe bottom, to the apparatus.